Google's opposition, which lasted 10 days, was a serious impediment for the software and for the ambitions of Brave CEO Brendan Eich to make a fresh start in the Web browser business. Eich was a Mozilla co-founder who led the Firefox browser project until his controversial departure in 2014. Without easy access to Android, Brave would have been cut off from a huge portion of the world's mobile users.

The initial opposition also shows just how hard it can be for developers to figure out why exactly they've run afoul of app store rules, even for developers as influential as Eich, who invented the JavaScript programming language that's a key foundation of the Web. Brave was "in a guessing game with Google," Eich said in an interview at this week's Mobile World Congress tech show in Barcelona.

You may hate online ads, but you probably appreciate free content from the likes of YouTube and Facebook that those ads support. Today, ads and free content are interdependent, but the growing use of ad-blocking technology is threatening that approach. It's not an exaggeration to say the future of much of what you do online hangs in the balance.

So about those ads

San Francisco-based Brave is trying to change the situation by adapting ad technology that is less intrusive to individuals and that lets online companies continue to run ad-supported businesses.

The startup blocks online ads and related tech that advertisers use to track and profile you when you visit websites. However, Brave will at times replace those ads with others targeted in a way designed to better respect user privacy. Specifically, the browser watches your browsing behavior and generates interest-area keywords it shares with a company called Sonobi that matches your keywords with the keywords of its supply of ads from ad agencies. Advertisers themselves don't see the keywords or know who they came from. The private browsing behavior data itself stays sealed up within the browser, and Brave says it doesn't know any of it -- or any other information about you.

Brave Software CEO Brendan Eich is on hand at Mobile World Congress 2016 to tout his new browser.

Stephen Shankland/CNET

Apparently Brave's approach befuddled Google's app checkers. They initially told Brave their browser violated section 4.4 of Google's Android Developer Distribution Agreement, which bars software that "interferes with, disrupts, damages, or accesses in an unauthorized manner the devices, servers, networks, or other properties or services of any third party including, but not limited to, Android users, Google or any mobile network operator."

Google declined to comment on why it rejected the initial app submission or Brave's first appeal two days later.

Sources familiar with the situation, though, said Google's initial assessment was that Brave blocked ads in other apps and that it took the intercession of an influential Google insider to help draw attention to the matter.

Brave, still in testing and missing many features available on competing browsers, is also available for Windows and Mac computers. The company faces an immense challenge attracting a large number of users in a browser industry that's highly competitive and dominated by tech giants Google, Apple and Microsoft.

Advertisers pay more to reach a specific audience they're targeting, giving online publishers and advertising companies a strong incentive to pry into your browsing behavior and personal details. But ad blockers strip out those ads. In addition to protecting privacy, ad blockers make websites load faster, free them from distracting pop-ups and protect people from malware that can be delivered through ad networks. Oh, and ad blockers mean that your phone battery lasts longer and that you hit your mobile network usage limits later.

Online advertising makes the Internet world go around. Research firm eMarketer expects says spending on digital ads reached $170.17 billion worldwide in 2015. PageFair, a company that tries to help publishers show minimally intrusive ads that ad-blockers won't block, believes 198 million people actively use ad blockers. Wired magazine earlier this month announced it will restrict content to people using ad blockers unless they disable ad blocking for Wired or pay $1 a week.

Eich's Firefox thrived on blazing its own trail, but Brave is reusing browser technology from other efforts. On Android, it builds on the work of Link Bubble, which is based on Google's core browser technology and which Brave acquired several months earlier. Link Bubble's original creator, Chris Lacy, is an independent programmer. On iPhones, Brave uses Apple's browser software. On computers, it uses the foundation of Google's Chrome browser.

Correction, 11:28 p.m. PT:A description of how browsing-related keywords are matched to ads with Brave's browser has been corrected. A company called Sonobi performs the matching.